Ever since Pennsylvania began using computerized voting machines a decade ago, critics have worried that hackers could throw an election by shifting votes from one column to another. But that’s far from the only fear in 2016, a year when Illinois’ voter registration database has been hacked and Democratic Party emails were purportedly raided by Russian hackers. “People have talked about Russia supporting Donald Trump,” said University of Iowa computer science professor Douglas Jones, who co-authored a 2012 book about election security. “But I think it would be to their advantage just to have a chaotic election, one that would weaken whoever won. … And if you wanted to cook an election, you don’t have to do anything massive.”
… Concerns this year are more likely to focus on Pennsylvania. Two-thirds of its counties, including vote-rich Allegheny and Philadelphia, use touch-screen voting machines for which there is no paper ballot. If a hacker corrupted or deleted those machines’ vote counts, there would be no physical ballots to reference.
“There are six or 10 states that very heavily use paperless touch-screen machines” said Andrew Appel, a Princeton University professor who studies voting machine vulnerabilities. “Of them, Pennsylvania is the biggest swing state.”
… Jones, the Iowa professor, said officials have to walk a tightrope, preparing for the worst without undermining public confidence. “I get emails from the conspiracy fringe listing legitimate sources, including me, saying these aren’t potential weaknesses, but things that have already been exploited,” he said.